In general, in the washing machines, there are pulsator type washing machines in which washing is made by a water circulation generated by a rotating pulsator, drum type washing machines in which washing is made by head and friction of washing water and laundry formed inside of a drum as the drum laid substantially in a horizontal direction is rotated, and agitator type washing machines in which washing is made by using rotation force of an upright agitator.
In the meantime, recently, a washing machine, particularly, a drum type washing machine is suggested, in which washing and the like are made with steam. If the washing is made with the steam, water and electricity can be saved, the washing performance can be enhanced, and generation of static electricity can be prevented. Moreover, wrinkle and smell can be removed from the laundry.
A related art drum type washing machine with a steam generator will be described, with reference to FIG. 1.
The related art drum type washing machine is provided with a cabinet 10 which forms an exterior of the washing machine, a cylindrical tub 20 supported in a horizontal direction in the cabinet 10 for holding washing water, a drum 30 rotatably mounted in the tub 20, and a driving motor (not shown) for driving the drum 30. The cabinet 10 has a laundry opening 13 in a front in communication with an inside of the drum for introduction/taking out laundry to/from the drum 30, with a door 11 mounted thereon for opening/closing the laundry opening 13. At one side of the drum type washing machine, there is a water supply valve 15 connected to an external water pipe (not shown) for supplying washing water to the tub 20. In general, between a detergent box 27 and the water supply valve 15, there are a hot water pipe 25a and a cold water pipe 26 connected thereto.
In the meantime, in the related art drum type washing machine, there is a steam generator 50 for supplying the steam to the inside of the drum 30, with a water supply hose 25 for supplying water and a steam hose 53 for supplying steam to the drum 30 connected thereto. In general, the water supply hose 25 is connected to a hot water side of the water supply valve 15. It is preferable that the steam hose 53 has a nozzle shaped end for smooth spray of the steam into an inside space of the drum 30, preferably with the nozzle shaped end through which the steam is sprayed exposed to the inside of the drum 30.
The steam generator 50 will be described in more detail with reference to FIGS. 2 and 3.
The steam generator 50 is provided with a lower housing 81 which forms an exterior of the steam generator 50 and a space for holding water, an upper housing 82 secured to an upper side of the lower housing 81, and a heater 55 for heating the water in the steam generator 50.
At one side of the upper housing 82, there is a water supply opening 52b connected to the water supply hose 25 for supply of the water to an inside of the steam generator 50, and at the other side of the upper housing 82, there is a steam discharge opening 52a connected to the steam hose 53 for supplying the steam to the drum 20.
The heater 55, mounted on a bottom of the lower housing 81, is operated in a state fully submerged in the water when the water is introduced into the steam generator 50. For this, mounted to one side of the upper housing 82, there is a water level sensor 60 for sensing a water level of the water held in the steam generator 50. The water level sensor 60 measures the water level inside of the steam generator 50 for always maintaining an appropriate level of the water. That is, if the water level in the steam generator 50 is lower than a reference value (a low water level), the water supply valve 15 is opened, to supply the water, and, if the water level of the inside of the steam generator 50 reaches to a reference value (high water level), the water supply valve 15 is closed, to stop supply of the water, and the heater 55 is put into operation, to generate the steam.
In the meantime, there is a temperature sensor 57 mounted thereto for measuring temperatures of the water heated by the heater 55 and the steam. The temperature sensor 57 is used for turning off power to the heater 55 to prevent the heater 55 from overheating if the temperature of the steam generator 50 measured by the temperature sensor 57 is higher than a reference value.
The water level sensor 60 will be described.
The water level sensor 60 is provided with a receptacle housing 61 which forms an exterior of the water level sensor 60 and provided for securing the water level sensor 60 to the steam generator 50, electrodes 62, 63, and 64 under the receptacle housing 61 for sensing water levels of the steam generator 50. In order to sense water levels of the steam generator 50, the electrodes 62, 63, and 64 are mounted to appropriate heights from the bottom of the lower housing 81. The electrodes are a common electrode 62 which is a reference electrode for sensing a minimum water level, a low water level electrode 63 for sensing a low water level, and a high water level electrode 64 for sensing a high water level. It is preferable that the common electrode 62 has a length at least the same with or longer than the low water level electrode 63.
In the meantime, if the water boils, many bubbles are formed suddenly, which are liable to stick to the electrodes 62, 63, and 64, to cause malfunction of the steam generator 50. Moreover, the water supplied through the water supply opening 122 is liable to splash to the electrodes, to cause malfunction of the steam generator. Moreover, it is difficult to avoid a certain level of vibration during operation of the washing machine, which is liable to cause washing of the water in the stream generator. Therefore, in order to prevent the water level sensor 70 from malfunctioning due to those, the water level sensor 70 is provided with a housing 70. Basically, the housing 70 surrounds the electrodes 62, 63, and 64 and an opened bottom. It is preferable that the housing 70 has an opening 70s. 
However, the related art steam generator in a washing machine and a washing machine therewith has the following problems.
Referring to FIG. 5, the related art steam generator is rectangular substantially, with a low height L1 and a large width L12. Therefore, it is not easy to mount the steam generator to the washing machine. Because, though the steam generator in general mounted to an upper portion of the washing machine, i.e., between the cabinet and the tub, a space t between the tub and the steam generator is not large. Moreover, because valves, hanging springs, and the like are mounted in the space between the cabinet and the tub, there is not so large surplus space. Accordingly, in the related art, mounting of the steam generator is not easy, and the steam generator suffers from damage caused by interference during movement of the washing machine. Moreover, because there is comparatively small gap, the steam generator is liable to collide to suffer from damage due to vibration coming from operation of the washing machine. Moreover, replacement of components is not easy.
On the other hand, it is required to improve performances of the steam generator, such as water consumption, energy efficiency, a steam generating time period, safety, and the like.